Structural and electronic properties of InGaN/GaN nanowires by the use of EELS



Electron energy loss spectroscopy (EELS), in both the low loss and the core loss regions of the spectra, have been used to study local alloys composition, electronic transitions and bonding environment of different species in nanowires consisted of a GaN base-part and a superlattice upper part of InxGa1–xN nanodisks (NDs)/GaN barriers. Experimental valence (low loss) electron energy loss spectroscopy (VEELS) spectra were taken from the GaN base-part, the GaN barriers and the InxGa1–xN disks. Electron energy loss near edge structure (ELNES) spectra presenting the C K-edge, the N K-edge, the In M4,5-edge were obtained from the GaN base-part and spacer and the InxGa1–xN NDs. Variation of In concentration as well as different strain states change the intensity and result in the broadening and shifting of the edges in the spectra. The TELNES.2 program of the WIEN2k code (Blaha et al., Comp. Phys. Commun. 59, 399 (1990) [1]) was implemented in order to study the electronic properties of InxGa1–xN. The N K-edge that represents the energy loss of the electron transition from the 2p to the 1s state is unique for each structure. Details on the bonding environment of the structure were extracted from the simulations of the ELNES spectra. Moreover, the influence of the In content in the InxGa1–xN NDs on the N-K edge was interpreted. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)